Non-quantal acetylcholine release at mouse neuromuscular junction: effects of elevated quantal release and aconitine.
The rate of non-quantal acetylcholine (ACh) release was estimated at the mouse neuromuscular junction by observing the effect of (+)-tubocurarine on endplate membrane potential or current in preparations pretreated with an irreversible anti-acetylcholinesterase (anti-AChE). Voltage clamping was an effective method for measuring non-quantal release. Non-quantal release was markedly inhibited by 10 microM aconitine. Non-quantal release was not significantly increased by 10 microM dihyroouabain (DHO). (It has been reported that ouabain increases the leak). Non-quantal release was roughly doubled following exposure to hypertonic solution or to elevated K(+)-solution. This is in accord with the hypothesis that the leak is by way of ACh transporters incorporated into the terminal membrane following exocytosis, but other interpretations remain to be tested.
Yu
S P
SP
Department of Physiology, Health Sciences Center, SUNY, Stony Brook 11794.
Van der Kloot
W
W
D000109:Acetylcholine / Q000378:metabolism*; D000157:Aconitine / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000294:innervation; D005260:Female; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009045:Motor Endplate / Q000187:drug effects / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects / Q000502:physiology*; D010042:Ouabain / Q000031:analogs & derivatives / Q000494:pharmacology; D011789:Quantum Theory; D014403:Tubocurarine / Q000494:pharmacology
C000977:dihydroouabain; D010042:Ouabain; D000109:Acetylcholine; D014403:Tubocurarine; D000157:Aconitine